PostgreSQL UNION
PostgreSQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows
postgres=# select * from tab1; postgres=# select * from tab2;
id | name id | name
----+------- ----+--------
1 | nijam 1 | jamal
2 | abu 2 | smith
3 | umar 4 | daniel
7 | jamal 5 | zaheer
(4 rows) (4 rows)
-- From above table tab1 and tab2 having one duplicate values "name=jamal" is duplicate so union clause shows only one rows of tab1 table (7,jamal), table tab2 duplicate row will not show
postgres=# select name from tab1 union select name from tab2;
name
--------
smith
daniel
zaheer
nijam
abu
jamal
umar
(7 rows)
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